This invention relates generally to sleeper compartments of the type used on over-the-road trucks, such as tractor-trailers and the like, and more particularly to sleepers which are aerodynamically contoured to minimize wind resistance and drag.
It is common to provide sleeping compartments on over-the-road trucks, such as tractor-trailer trucks and the like. The sleeping compartment generally provides one, and sometimes two, sleeping bunks for the truck operators, and may include storage areas for luggage, tools, and the like, as well as convenience items such as a small refrigerator. Sometimes, the sleeper compartment is built-in integrally with the truck cab, but usually it comprises a separate unit. Known sleeper units are generally squared-off box-like structures which are mounted on the truck chassis behind the truck cab. Access into the sleeper may be provided by a passageway through the rear wall of the truck cab and the front wall of the sleeper. Typically, the front wall of the sleeper is a flat transversely extending surface which projects laterally beyond the sides of the cab, and may project upwardly above the roof of the cab. The projecting portions of the front wall thus may have substantial wind resistance and may create substantial drag.
It is well known that wind resistance and drag reduce fuel efficiency and increases operating costs. With tractor-trailer trucks, the wind resistance and the resulting drag presented by the front wall of the trailer, particularly that portion which extends above the roof of the cab, may be substantial, and it is known that by reducing this drag significant improvements in operating efficiency and fuel economy may be obtained. Accordingly, various techniques and devices have been employed for streamlining truck cabs and/or trailers to reduce their wind resistance and to afford a smooth air flow over their surfaces.
It has been proposed, for example, to shape aerodynamically the body of a truck cab and/or a trailer so as to minimize their wind resistance. While this technique is capable of substantially minimizing wind resistance and drag, it has the disadavantages of being expensive and impractical in many cases. Another approach which has become quite common is to attach air fairings to the truck cab for deflecting the air flow around or over the trailer. Typically, such air fairings comprise an air deflecting member attached to the roof of the truck cab and arranged to slope upwardly toward the rear so as to direct the air flow upwardly over the top of the front wall of the trailer and, to some extent, outwardly around the sides of the front wall near the top. Although such devices are helpful in reducing the wind resistance of the trailer, they are not entirely satisfactory. They do little, for example, to reduce the wind resistance of the portion of the trailer below the level of the cab roof. Moreover, there is often a substantial distance between the trailing edge of the air fairing (and the rear of the cab) and the front wall of the trailer which allows the air leaving the fairing to "swirl" and creates turbulent air flow. Thus, the air fairing may be only partially effective in reducing the wind resistance and drag of the trailer.
Very little has been done to address the problem of minimizing the wind resistance and drag of a sleeper unit attached to a truck. For vehicles having an integral built-in sleeper, this may not be a problem since the sleeper is typically formed as a rear ward extension of the cab body, and it may not present any transversely extending surfaces which would resist the air flow past the cab body. With removable sleepers, however, the situation is different. Truck cabs vary widely in size and shape, and it has not been feasible or cost effective to produce a variety of different sleepers to match the different truck cabs. Removable sleepers are typically constructed in standard sizes so that they may be used with a number of different truck cabs. Such sleepers normally extend somewhat beyond the lateral sidewalls of the cab, and these extending portions may present substantial wind resistance and drag. Other than sizing sleepers to match generally the width of truck cabs and minimize the amount by which the sleepers project beyond the sidewalls of the cab, very little consideration has been given to the aerodynamic performance of the sleepers.
It is desirable to provide removable sleeper apparatus which avoid the foregoing and other disadvantages of known sleepers, and it is to this end that the present invention is directed.